Fan shaft router (Ultimaker)

**What**: parts for the shaft engines blowing.
**What for**: direction of air flow from the fan up the shaft and sideways into the blowing grille.
**For whom**: the owners of Ultimaker (and its clones) with a body material thickness of 6 mm (with air shafts).

The standard design of the blowdown shaft of XY engines and extruders has two drawbacks:
1) the fan below blows _perpendicularly_ into the wall of the shaft, thereby _lowing_ the speed of the air flow and directing it into _not the ri